1. Field of the Invention
The present invention relates to circuit breakers. More specifically, the present invention provides a pair of spacer pins for the shunt wires within the circuit breaker.
2. Description of the Related Art
A typical circuit breaker includes both a thermal trip mechanism and a magnetic trip mechanism for moving the arm having the movable contact away from the fixed contact when an over-current is present. The trip unit includes a bimetal connected at its fixed end to the load terminal, and at its free end to a shunt, which is connected to the contact arm. A trip bar mounted adjacent to the bimetal includes a thermal trip arm and a magnetic trip armature. The trip bar engages a latch on the operating mechanism for tripping the circuit breaker.
In use, current will flow from the line terminal, through the fixed contact, through the movable contact and arm, through the shunt, through the bimetal, and then through the load terminal. When a persistent low level over-current occurs, the heating of the bimetal will cause it to bend until it strikes the thermal trip arm of the trip bar, thereby tripping the circuit breaker. A larger over-current will cause the magnetic trip armature to be attracted toward the bimetal by a magnetic field generated by a short circuit current flowing through the bimetal, again rotating the trip bar and tripping the circuit breaker.
During a high interruption capacity test, it is possible for magnetic attraction caused by current flow in the same direction to cause the shunt wires to come together, thereby causing mechanical interference preventing movement of the thermal trip arm, thereby preventing tripping of the circuit breaker. Accordingly, there is a need for a means for maintaining proper spacing between the shunt wires to maintain proper function of the circuit breaker.
The present invention provides a pair of shunt wire spacer pins for maintaining the proper distance between the shunt wires within a circuit breaker. The shunt wire spacer pins depend upward from the back of the housing of the circuit breaker, extending up between the shunt wires. The shunt wire pins may be made of any suitably rigid material, such as metal or plastic.
In use, the shunt wire spacer pins depend upward from the housing wall, between the shunt wires, with each pin corresponding to one of the two shunt wires. With the shunt wire spacer pins in place, the shunt wires are held the proper distance apart to permit proper movement of the circuit breakers"" thermal trip arm.